Servo-operated valve

ABSTRACT

A single chamber two-way servo-operated valve comprising: a valve body ( 1 ) presenting an inlet aperture ( 2 ), an outlet aperture ( 3 ) and an access ( 11 ); a cover ( 12 ) to close the access ( 11 ) of the valve body ( 1 ); a port ( 4 ) dividing the valve body interior into an inlet section ( 5 ) and an outlet section ( 6 ); a valving element ( 8 ) comprising a disc ( 10 ) for closing said port ( 4 ); and an actuating chamber ( 15 ) at least partially defined by the cover ( 12 ), the disc ( 10 ) and a flexible diaphragm ( 14 ) connected to the valving element ( 8 ), the disc ( 10 ) of said valving element ( 8 ) comprising a rigid central core ( 50 ) which is at least partially covered by a rubber layer ( 18 ) adhering to said central core ( 50 ), said rubber layer ( 18 ) extending from the edge of the disc ( 10 ) to form the flexible diaphragm ( 14 ).

The present invention relates to a single chamber two-way servo-operatedvalve in accordance with the introduction to the main claim.

In the state of the art two-way servo-operated valves present a valvingdisc which closes a port and is keyed onto a stem controlled by anactuator which can be of separated chamber or single chamber type.

In separated chamber models the actuator comprises a rigid actuator discwith a connected diaphragm which is clamped onto the end of the actuatoredge by a cover, to hence divide the actuator volume into a firstchamber on one side of the actuator disc and a second chamber on theopposite side. The two chambers are completely separated from each otherand from the fluid which flows through the valve. Normally the actuatordisc is composed of two superposed discs keyed onto the stem, betweenthem there being clamped the diaphragm which is holed in the centre forpassage of the stem. In this manner the diaphragm is connected to theactuator disc and follows its movements by flexing. An actuator fluidenters one of the actuating chambers to control the movement of theactuator disc and of the valving element keyed onto the same stem.

The actuator fluid can be the same as that flowing through the valve andwithdrawn upstream of its entry into the valve, but is generally adifferent fluid at higher pressure, to achieve a smaller-dimensionactuator.

In single chamber valves there is only one actuating chamber defined bythe inner surface of a cover, by a side of the actuator disc and by theflexible diaphragm connected to it, the edge of which is clamped betweenthe cover and the valve body. The fluid to be intercepted by the valveflows on the other side of the actuator disc and acts on the actuatorwith its pressure. In this case the function of the actuator disc and ofthe valving disc can be performed by a single actuator/valving disc(hereinafter known simply as “disc”). It currently consists of twosuperposed discs keyed onto a stem, between them there being clamped adiaphragm holed in its centre for passage of the stem, its edge beingclamped between the cover and the valve body to separate the actuatingchamber from the fluid flowing through the valve, to enable the valvingelement to move with diaphragm flexure.

The fluid fed into the actuating chamber for valve operation is normallythe same as that flowing through the valve, withdrawn upstream of theport to be closed by the valving element.

When the fluid withdrawn upstream of the port is fed into the actuatingchamber it presses against the disc and, possibly aided by a spring orelastic member, closes the valving element by overcoming the pressureexerted by the fluid flowing through the valve on the other side of thedisc, separated from the actuating chamber. To obtain movement in theopposite direction, the actuating chamber has merely to be emptied.

The stem normally emerges from the cover to visually indicate the valveopening or closure state. This reduces the active surface of the disc onthe actuating chamber side.

Even though a single chamber valve represents a considerableconstructional simplification compared with a double chamber valve, itstill comprises a considerable number of component parts: a flexiblediaphragm, an actuator/valving disc formed in two parts to clamp thediaphragm, a stem, a gasket for sealing the valving disc against theedge of the port to be closed, and a clamping element between the stemand discs.

The large number of parts also results in complicated assembly,resulting in longer times and possible errors.

Simpler single chamber valves also exist in which the valving element isformed from a simple fabric-incorporated rubber diaphragm, with valvingelement inflexion for opening. However such valves cannot be used inapplications in which the operating pressures are high, and also resultin less precise operation, for which reason they are excluded fromcertain specifications.

An object of the present invention is therefore to provide a hydraulicvalve by which the stated drawbacks are overcome, and in particular atwo-way servo-operated valve formed from a small number of componentparts and hence with low production cost.

Another object is to provide a hydraulic valve which is simple and quickto assemble and disassemble.

A further object is to achieve simpler and hence less costly componentparts.

Said objects are attained by a valve, by a valving element and by acover, the inventive characteristics of which are defined in the claims.

The invention will be more apparent from the ensuing detaileddescription, provided by way of non-limiting example, of a preferredembodiment of the valve, of the cover and of two preferred embodimentsof the valving element, illustrated in the accompanying drawings, inwhich:

FIG. 1 is a perspective view of a section of the valve according to theinvention, obtained by sectioning the valve body and the valving elementalong two perpendicular planes and the cover along a longitudinal plane;

FIG. 2 is a longitudinal section through the valve with a firstembodiment of the valving element;

FIG. 3 is a perspective view of the valve and valving element withoutthe cover;

FIG. 4 is a perspective view of a second embodiment of the valvingelement alone.

With reference to FIG. 1, it can be seen that the two-way valvecomprises a valve body 1 flanged at its two ends, with a cover 12closing an access 11. Said cover comprises a lateral flange 29 to beconnected to a flange 30 provided on the valve body 1. This valve can beused to intercept liquid and gaseous fluids of various types, morecommonly water, oil and liquids in general, but also gases and vapours.

With reference to FIG. 2 it can be seen that this valve is of the singlechamber type. The valve body presents in its interior a flow tube withan inlet aperture 2 and an outlet aperture 3, between which the circularport 4 is positioned to separate the flow tube into an inlet section 5and an outlet section 6. The edge of the port 4 carries a metal sealring 7 screwed into its seat.

At the port 4, the valve body 1 presents an access 11 to be closed by acover 12, the edge of which forms a lateral flange 29 for connection tothe valve body 1.

A valving element 8 is disposed at the port 4 and at the access 11 toclose or open the port 4 by a translational movement.

Said valving element 8 comprises a disc 10 to close the port 4 and astem 9 to guide the travel of the valving element 8. The disc 10 of thevalving element 8 comprises a rigid central core 50 covered with arubber layer 18 adhering to said central core 50. Said rubber layer 18extends from the edge of the disc 10 to form an annular flexiblediaphragm 14. The diaphragm 14 is clamped peripherally between the valvebody 1 and cover 12 to define, together with the inner surface of thecover 12 and the upper side of the disc 10, an actuating chamber 15separated from the flow tube. The edge of the diaphragm 14 to be clampedbetween the cover 12 and valve body 1 forms a gasket ring 19, to beinserted into suitable seats in the cover and valve body to hence ensurethe seal. The flexible diaphragm 14 hence extends from the surface ofthe disc 10 and is formed by the extension of the rubber layer 18 beyondthe edge of the rigid central core 50 of the disc 10. The disc 10 andflexible diaphragm 14 form a single element with rigid and flexibleparts which are not mutually separable. The disc 10 presents said rubberlayer 18 over its entire surface, in particular in that region intendedto rest on the seal ring 7. In this respect, the rubber layer 18 alsoacts as a gasket to provide a seal when the disc 10 presses against theseal ring 7 to close the port 4. In proximity to the central core 50 thediaphragm 14 presents a greater thickness than that of the free partsdistant from the central core 50, these free parts being those parts ofthe diaphragm 14 not clamped between the cover 12 and valve body 1. Theflexible diaphragm 14 is preformed by deep-drawing to form a cavity suchthat the valving element 8 lies naturally in the closure position forthe port 4 to facilitate, by its elasticity, the action of the fluid inthe actuating chamber 15 against the pressure of the fluid flowingthrough the flow tube on the opposite side of the disc 10. To withstandrepeated stresses the flexible diaphragm 14 is fabric-incorporated, andfor continuity the rubber layer 18 is also fabric-incorporated, at leaston one side of the disc 10. The central core of the disc 10 ispreferably of metal. The lower surface of the disc 10 presents a slightcentral swelling directed downwards (as in FIG. 2) or a convexity,making the opening and closure of the valving element 8 smoother. Thestem 9, which projects from only one of the two sides of the disc 10,can be made in one piece with the central core 50 or be removablyfixable to the disc 10. The stem 9 is constrained to slide within aguide 13 provided on the inner surface of the cover 12. For greaterconstructional simplicity, the stem 9 projects from only one side of thedisc 10 and the valve comprises, for the stem 9, only one guide,disposed on one of the two sides of the disc 10. The guide 13 is formedas a dead-ended hole. As the stem alone withstands the strong flexingmoments exerted on the valving element 8, it must have a sufficientlylarge cross-section. The stem 9 also presents longitudinal grooves whichconnect the base of said dead-ended hole 13 to the actuating chamber 15.These longitudinal grooves can also be present on the inner surface ofthe dead-ended hole 13. This results in a greater active surface of theactuating chamber 15, which is also useful in consideration of theconsiderable cross-section of the stem 9 compared with valves havingvalving elements guided on two sides of the disc. A small indicator rodcould emerge outwards from the end of the dead-ended hole to visuallyindicate the valving element position.

Both the guide 13 and the stem 9 are covered with coatings whichfacilitate their sliding and limit wear.

In the example of FIGS. 1 and 2 a spring 23 is also present, resting onthe inner surface of the cover 12 to urge the valving element 8 into theposition in which it closes the port 4 and to facilitate the action ofthe fluid within the actuating chamber 15.

The access 11 presents an outward flare acting as a support for thediaphragm 14 when the valving element 8 closes the port 4. The disc 10of the valving element 8 presents a thickness and diameter sufficient toprovide complete support for the diaphragm 14 on the flare of the access11 and hence prevent excessive deformation and stresses which thediaphragm 14 would undergo if unsupported. In the same manner the cover12 lowerly presents a convex central portion for supporting thediaphragm 14 when the valving element 8 is raised into the valve openposition.

The cover 12 presents two actuator holes 27, 28 in its central portion.In the valve body 1 the inlet section 5 presents an inlet hole 25, theoutlet section 6 presenting an outlet hole 26. The lateral flange 29 ofthe cover 12 presents two lateral through holes 31, 32 to overlie theinlet hole 25 and outlet hole 26. The flexible diaphragm presents twotabs (visible in FIG. 3) with two peripheral holes 33 and 34 to beinterposed between the cover 12 and valve body 1 in positionscorresponding with the lateral holes 31, 32 of the cover superposed onthe inlet hole 25 and outlet hole 26 of the valve body. The actuatingchamber 15 can hence be connected by suitable tubes (not shown forsimplicity) both to the inlet section 5 (by a tube connecting theactuator hole 27 to the lateral hole 31 superposed on the inlet hole 25)and to the outlet section 5 (by a tube connecting the actuator hole 28to the lateral hole 32 superposed on the outlet hole 26). Theseconnection tubes can evidently be connected together, and cocks,manometers and other devices can be connected to them. By thisconstructional arrangement, both ends of the connection tubes areconnected to the cover 12 with the considerable advantage that the covercan be easily separated from the valve body without having to disconnectthe tubes.

When in operation the fluid enters the valve through the inlet aperture2, occupies the inlet section 5 and, if the valving element 8 is raised,passes through the port 4, then below the disc 10 and the diaphragm 14,to reach the outlet section 6 and then leave the valve through theoutlet aperture 3. If the valving element 8 is lowered, the port 4 isclosed and the fluid occupying the inlet section 5 is unable to pass tothe outlet section 6, it remaining confined upstream of the port 4.

The valving element can be lowered by feeding a pressurized fluid intothe actuating chamber 15, immediately above the disc 10, through anactuator hole 27, while the other actuator hole 28 is closed. Thepresence of a fluid at sufficient pressure in the actuating chamber 15causes the valving element 8 to lower and close the port 4. The fluid ofsufficient pressure can be the same fluid as that flowing through thevalve, withdrawn upstream of the port 4 through the inlet hole 25.

The pressure of this fluid is sufficient to lower the valving element 8,both because the fluid flowing through the flow tube presents a lowerpressure by the effect of its velocity (Bernoulli effect), and becauseof the action of the spring 23, and again because the preforming of thediaphragm and its elasticity, inversely proportional to its thickness,favour the action of the fluid within the actuating chamber 15 and theclosure of the port 4 by the valving element 8.

When the connection between the actuating chamber 15 and the inletsection 5 is interrupted but the connection between the actuatingchamber 15 and the outlet section 6, or between the actuating chamber 15and the outside environment at atmospheric pressure, is open, the liquidflows from the actuating chamber 15 and the pressure of the liquidpresent below the valving element 8 causes it to rise, hence opening theport 4 and enabling the liquid to pass through it.

In FIGS. 1 and 2 it can be seen that in a first embodiment of thevalving element 8, the disc 10 and stem 9 are made in one piece. Thedisc 10 is completely covered with the rubber layer 18, while the stem 9presents a covering of antiwear material facilitating its sliding withinthe guide.

FIG. 4 shows a second embodiment of the valving element 8 with the discrubber-covered and the preformed flexible diaphragm 14 which extendsfrom the edge of the disc 10 forming a concavity on the same side as thestem 9. In this case the disc 10 can be separated from the stem 9. Thisembodiment is preferred in the case of large valve dimensions, becauseof which the valving element 8, if the stem and disc were made in onepiece, would be excessively bulky for transport.

Instead of being guided along the stem 9, the valving element 8 couldalso be guided along any element forming part of the valving element 8or rigidly connected thereto, for example fins (not present in theillustrated examples).

There are two rules relating to the length of a valve in relation to itsrated diameter: one is known in technical jargon as long ISO (ISO beingInternational Standard Organisation) and corresponding to DIN 3202 F1,and the other known as short ISO corresponding to DIN 3202 F5. Thepreformed diaphragm 14 enables an accentuated flaring of the access 11to be achieved, together with a smaller access diameter. This results ina shorter length of the valve, which can pass from the long ISO categoryto the short ISO category.

The valve of the invention comprises a smaller number of parts thancurrently existing single chamber two-way servo-operated valves. Becauseof the preforming of the diaphragm 14 and its elasticity, the spring canalso be superfluous.

The present patent also protects a valving element 8 of a servo-operatedvalve comprising a disc 10 with a rigid central core 50 at leastpartially covered by a rubber layer 18 adhering to said central core 50,said rubber layer 18 extending from the edge of the disc 10 to form aflexible diaphragm 14.

The diaphragm 14 can be preformed such as to form a concavityfacilitating the action of the fluid located on one side of the disc 10,against the fluid located on the other side.

Said valving element 8 can advantageously present two peripheral holes33 and 34 in proximity to that edge of the diaphragm 14 to be clamped.

The present patent also protects a cover 12 for a single chamber two-wayservo-operated valve, said cover 12 presenting a central portion withtwo actuator holes 27, 28 and a lateral connection flange 29 presentinga plurality of connection holes to receive bolts for its clamping to thevalve body and two lateral through holes 31, 32 for fluid passage.

1. A single chamber two-way servo-operated valve comprising: a valvebody (1) presenting in its interior a flow tube with an inlet aperture(2), an outlet aperture (3) and an access (11); a cover (12) to closethe access (11) of the valve body (1); a port (4) dividing the flow tubeinto an inlet section (5) and an outlet section (6); a valving element(8) comprising a disc (10) for closing said port (4); and a flexiblediaphragm (14) connected to the disc (10) to separate the flow tube froman actuating chamber (15) lying between the disc (10) and cover (12),characterised in that the disc (10) of said valving element (8)comprises a rigid central core (50) which is at least partially coveredby a rubber layer (18) adhering to said central core (50), said rubberlayer (18) extending from the edge of the disc (10) to form the flexiblediaphragm (14).
 2. A valve as claimed in claim 1, characterised in thatthe diaphragm (14) is preformed by deep-drawing such that the valvingelement (8) lies naturally in the position which it assumes when theactuating chamber (15) is under pressure.
 3. A valve as claimed in claim1, characterised in that in proximity to the central core (50) thediaphragm (14) presents a greater thickness than that of the free partsdistant from the central core (50).
 4. A valve as claimed in claim 1,characterised in that said flexible diaphragm (14) is clampedperipherally between the valve body (1) and cover (12).
 5. A valve asclaimed in claim 1, characterised in that the edge of the diaphragm (14)forms a gasket ring (19).
 6. A valve as claimed in claim 1,characterised in that said central core (50) is of metal.
 7. A valve asclaimed in claim 1, characterised in that said valving element (8)comprises a stem (9) made in one piece with the central core (50).
 8. Avalve as claimed in claim 1, characterised in that said valving element(8) comprises a stem removably fixable to the disc (10).
 9. A valve asclaimed in claim 1, characterised in that said valving element (8)presents a stem (9) which projects from only one side of the disc (10).10. A valve as claimed in claim 9, characterised in that the cover (12)presents a dead-ended hole (13) acting as a guide for the stem (9), thestem (9) or the dead-ended hole (13) presenting longitudinal grooveswhich connect the actuating chamber (15) to the end of said dead-endedhole (13).
 11. A valve as claimed in claim 1, characterised in that saidrubber layer (18) completely covers the disc (10).
 12. A valve asclaimed in claim 1, characterised in that the cover presents a centralportion with two actuator holes (27, 28) and a lateral flange (29) forits connection to the valve body (1), this latter presenting an inlethole (25) in the inlet section (5) and an outlet hole (26) in the outletsection (6), the lateral flange (29) of the cover (12) presenting twolateral through holes (31, 32) to be superposed on the inlet hole (25)and outlet hole (26) to connect the inlet section (5) and the outletsection (6) to the actuating chamber (15).
 13. A valving element (8) fora servo-operated valve, characterised by comprising a disc (10) with arigid central core (50) at least partially covered by a rubber layer(18) adhering to said central core (50), said rubber layer (18)extending from the edge of the disc (10) to form a flexible diaphragm(14).
 14. A valving element (8) as claimed in the preceding claim,characterised in that the diaphragm (14) is preformed to form aconcavity.
 15. A valving element (8) as claimed in claim 13,characterised by presenting two peripheral holes (33, 34) in proximityto that edge of the diaphragm (14) to be clamped.
 16. A cover (12) for asingle chamber servo-operated valve, said cover (12) presenting acentral portion with at least one actuator hole (27, 28) and a lateralconnection flange (29), characterised in that said lateral flange (29)presents two lateral through holes (31, 32) for fluid passage.